Synthetic diamond

Synthetic diamond is diamond produced through chemical or physical processes in a laboratory. Like naturally occurring diamond it is composed of a three-dimensional carbon crystal. Synthetic diamonds are also called cultured diamonds, manufactured diamonds, and artificial diamonds. Synthetic diamond is not the same as diamond imitation which can be made of other material such as cubic zirconia or Moissanite.

History

Synthetic diamonds were first produced on February 16, 1953 in Stockholm, Sweden by the QUINTUS project of ASEA, Sweden's major electrical manufacturing company using a bulky apparatus designed by Baltzar von Platen and the young engineer Anders KÃ¤mpe (1928 to 1984). Pressure was maintained within the device at an estimated 83,000 atmospheres (8.4 GPa) for an hour. A few small crystals were produced. The discovery was kept secret.

Nevertheless, General Electric researchers reported their own successful diamond synthesis in Nature. The production of smaller synthetic diamonds and especially diamond dust has become an important industry with General Electric at the forefront. General Electric, along with Sumitomo Electric and De Beers marketed their synthetic stones as heat sinks for electronics and used them solely for research purposes.

Significantly, the majority of these synthetic diamonds are not of gem quality. However, they are of adequate quality for industrial applications. As of 2004, two companies have proposed high-quality synthetic diamonds to the jewelry market.

Synthetic gems

While visiting Moscow in 1995 someone asked Carter Clarke if he wanted to buy a diamond making machine. He brought the machines and the scientists to Sarasota, Florida and started the first diamond making company, Gemesis. Gemesis grows diamonds in high-pressure, high-temperature crystal growth chambers that resemble washing machines. The device bathes a tiny sliver of natural diamond in molten carbon at 1500 ÂºC and 58,000 atm (5.9 GPa). This produces a 2.8 carat (560 mg) rough diamond which can be cut to 1.5 carats (300 mg). Gemesis diamonds have a yellow tint that is rare in natural diamonds and therefore a valuable aesthetic trait. The yellow tint occurs when less than five out of each 100,000 carbon atoms in the diamond crystal lattice are replaced with nitrogen atoms. Technically it is a contaminant, but colored diamonds are more profitable because they can be made more quickly, cost less to manufacture, and are very popular.

A second company, Boston, Massachusetts-based Apollo Diamond, uses the low-pressure technique of chemical vapor deposition (CVD) to produce larger, less expensive diamonds with greater control over impurities. The diamond produced is a single crystal, as opposed to the polycrystalline patchworks formerly produced by CVD. This greater measure of control allows Apollo Diamond to produce diamonds of various colors, from pink to black. The ability to control the intentional introduction of impurities, doping, is necessary for the creation of diamond semiconductor devices.

Both types of diamonds mentioned above are visually indistinguishable from the naturally occurring ones. However, the companies have taken steps to ensure that they can be distinguished by laser inscription, trace impurities, and infrared and X-ray spectroscopy. The diamonds are being marketed at $4,000 per carat ($20,000/g), or roughly 30% less than the price of a comparable natural diamond. The traditional diamond industry is evaluating countermeasures to these cheaper alternatives. (sources : Wired.com, Chemical and Engineering News: The Many Facets of Man-Made Diamonds).

Other uses

Given the extraordinary set of physical properties diamonds exhibit, large, cheap diamonds could have a wide-ranging impact in many fields.

The Carnegie Institute's Geophysical Laboratory can produce 10 carat (2 g) single-crystal diamonds rapidly (28 nm/s) by CVD, as well as colorless single-crystal diamonds. Growth of colorless diamonds up to 60 g (300 carats) is believed achievable using their method.⁽¹⁾

The CVD produced diamonds have been targeted for their potential use in technology. For example, University of Wisconsin, Madison chemistry professor Robert Hamers has developed a photochemical methods for covalently linking DNA to the surface of polycrystalline diamond films produced through CVD. Also, the diamonds have been shown to detect redox reactions that can't ordinarily be studied and in some cases degrade redox-reactive organic contaminants in water supplies.

The diamonds also have potential uses in the semiconductor industry. This is because the diamonds can be "doped" with impurities like boron and phosphorus. Since these elements contain one more or one less electron than carbon, they turn the diamonds into n-type or p-type semiconductors. There are also studies being conducted about impregnating boron-doped CVD diamonds with deuterium yields to produce n-type semiconducting diamonds.

References

Note (1): "Real big diamonds made real fast". Science Blog. URL accessed on September 14, 2005.

External links

Davis, J. (2003). The New Diamond Age Wired Magazine, Issue 11.09
Yarnell, A. (2004). The Many Facets of Man-Made Diamonds. Chemical and Engineering News 82 (5), 26-31.
Hall, H. T. (1961). The Synthesis of Diamond Journal of Chemical Education, 38, 484
Carnegie Institution's Geophysical Laboratory
Gemesis Cultured Diamonds
Apollo Diamond, Inc.